Kirk,
If your friend who now dates women after dating men made a big deal about his "conversion", became insufferable by telling all his gay friends that they should do the same, became a poster-boy for the ex-gay movement, then, sure, I would expect most gay people to make fun of him or rebuke him.
For what's it's worth, if a guy who had always dated women came out of the closet with the announcement that he "would no longer engage in heterosexual behavior", I'd probably make fun of him, too.
I had a friend from college who tried heterosexual marriage. He hadn't had any luck finding a boyfriend who wanted a family. He found a woman his age who agreed to marry him. She was a professional and educated and came from a culture where arranged marriages are common and marriages based on factors like stability, resources, kindness, etc. are valued more than sexual attraction. They were good friends. Marrying seemed logical... to them. There was no money exchanged, no visa issues, they just got married. His gay friends attended the wedding, one as his best man. Sure, people talked to him A LOT before they accepted it, but they accepted it, celebrated it.
The couple divorced a few years later. No kids, fortunately. No rancor either. Still friends. He later found a partner, another man, and they're still together, almost 20 years later. She went on to marry another man, too.
